Internal combustion engine



June 29, 1937, aw, M H 2,085,035

INTERNAL COMBUS TION ENGINE Filed Oct. 22, 1954 3 Sheets-Sheet l June29, 1937.

G. W. MEREDITH INTERNAL COMBUSTION ENGINE Filed Oct. 22, 1934 3Sheets-Sheet 2 June 29, 1937.

G. W. MEREDITH INTERNAL COMBUSTION ENGINE 5 Sheets-Sheet 3 Filed Oct.22, 1934 Patented June 29, 1937 ire r'rEs wears PATE'E FE'EQE 8 Claims.

The two-cycle type of gas engine (the term gas engine being hereinafteremployed as synonymous with internal-combustion engine), While extremelysimple from the standpoint of the mechanism therein employed, isordinarily deficient in performance and in fuel economy when operatedunder loads which are small fractions of the engines full load capacity.Furth rmore, the two-cycle does not run smoothly at low throtn tleexcept it be supplied with a mixture overrich in fuel in order to ensureignition of the mixture. The latter defect in operation is due to thedifiiculty of providing an ignitable mixture at the igniter, because ofthe preponderance L", of burned gas remaining in the cylinder, the

result of a previous explosion. It is characteristic of the two-cyclegas engine that the compression pressure is approximately the same atlow throttle as at full throttle, for the reason that the partialvacuum, produced in the cylinder by throttling the mixture, will drawgas into the cylinder from the exhaust passages.

The engine hereinafter described and illustrated in the accompanyingdrawings was invented for the purpose of securing an engine which wouldnot be subject to the objections above enumerated. It is similar inseveral respects to the engine illustrated and described in my priorapplication filed Aug. 31, 193A, and bearing Serial No. 742,277, seriesof 1925. In the present engine, I have incorporated the features of theengine which is the subject of my prior application, and have addedthereto certain additional features hereinafter illustrated anddescribed.

As in the engine described in my prior application, one object of myinvention is to provide means whereby a more intimate mixture of thefuel and the air may be secured than is customarily obtained intwo-cycle engines in general use. Another object is to secure a certainmeasure of stratification between the new charge and such exhaust gasesas may remain from a previous explosion. Another object is to secure, bythis stratification, a certain measure of isolation of the fresh chargefrom residual exhaust gases in proximity to and surrounding the firstpoint of. ignition. Another object is to provide unidirectional flow ofthe exhaust gases and the entering charge thereby to minimize dilutionof the latter by exhaust gases. In addition to the above objects, theinvention which is the subject of the presen application has for itsobject the securing of a greater freedom for the entering charge, and afuller distribution of the charge throughout the cylinder.

In processing my invention, I retain the passage between the crankcaseand the closed end of the cylinder as in my prior application, and inaddition thereto I incorporate in the cylinder wall a by-pass similar tothat employed in the majority of two-cycle engines, together with theby-pass port customarily provided in such engines. I retain the pistonport provided in my prior design, and arrange it so that it willregister with the entrance to the pass-age at the end of the powerstroke. I also provide an exhaust port in the cylinder wall on that sideof the cylinder opposite the passage. I attach to the piston adeflecting plate, of the same general type customarily employed intwo-cycle engines. As the piston approaches the end of the power stroke,it first opensthe exhaust port, then the passage port, and finally theby-pass port. As mixture enters the cylinder from the by-pass, it isdeflected toward the closed end of the cylinder by the deflecting plateattached to the piston. As this portion of the new charge meets thatentering the closed end of the cylinder'frorn the passage, eddies arepromoted to increase the turbulence, which is promoted at the entranceof the fresh charge into the cylinder from the passage as follows:

The exit from the passage into the closed end of the cylinder is sodirected that the path of the entering charge is pointed toward the wallof the cylinder in one type of admission port and toward the wall of thecylindrical mouth of a second type of admission port. Thus the column ofentering gas is induced to follow a path tangential to the cylindricalsurface and thereby go into a spiral swirling motion. As this portion ofthe charge meets that entering from the by-pass, turbulence in alldirections is promoted. The intimacy of the mixture promoted by theturbulence tends toward perfection of combustion, high means effectivepressures and maximum economy of fuel.

The passage referred to is provided in the wall of the cylinder, andprovides a conduit for the mixture to flow from the crankcase to theclosed end of the cylinder. The cylinder end of the passage is open atall times to the cylinder and in it is comprised a portion of thecombustion space, into which the mixture is compressed at the end of thecompression stroke. Since the combustion space is comprised of both thepassage and the clearance between the piston and the cylinder head atthe end of the compression stroke it is of an attenuated form. Thisrequires special arrangement of the ignition means.

As in the engine described in my prior applito provide the necessaryseal.

cation, I so locate the spark plugs or other ignition means that one islocated close to the passage port and another in proximity to the exitfrom the passage into the cylinder. Since the rush of the fresh mixtureentering from the crankcase will drive from the passage any products ofcombustion remaining from a previous explosion, there will be freshmixture, undiluted by exhaust gases, in proximity tothe passage port.Therefore, the points of the spark plug located close to the passageport will be surrounded by fresh mixture, and ignition be assuredregardless of how low the engine may be throttled. Thus the skipping ofexplosions, or missing which is a characteristic of both twoandfour-cycle engines at low throttle, is avoided.

Owing to the attenuated form of the combustion space, ignition by onespark plug alone, especially if the plug is located near one end of thecombustion space, would cause a long period of inflammation. If but theone plug at the entrance to the passage were to be used, flamepropagation to opposite end of the combustion space would be slow, andthe performance of the engine would be sluggish. The second plug at theexit of the passage into the cylinder provides for rapid spread ofcombustion and a short period of inflammation.

The filling of the passage with fresh mixture is assured for the reasonthat the passage port is opened in advance of the by-pass port, andtherefore at a time when the pressure in the crankcase is at a maximum.

When the piston port is out of registration with the passage port, thepassage port is closed by the outer surface of the piston wall. Sincethe piston must be free to reciprocate in the cylinder, there must be acertain amount of space between the piston and the inner wall of thecylinder. This space increases as the piston and the cylinder wear fromuse. Were no means provided to seal this space, gas under pressure ofthe explosion would enter, and pass around the piston to the exhaustport. Piston rings offer a means However, in order to provide suficientsealing, it would be necessary to provide rings around almost the entirelength of the piston. Fortunately, means presents itself for providingthe required seal without resort to a multiplicity of piston rings.

During the compression stroke, pressure is not generated in the cylinderuntil the piston has covered the exhaust port. Half the remaining strokeis completed before the pressure is of appreciable amount or about 20pounds gauge. The lubricating oil should provide ample seal against theescape of gases under this low pressure. For the remainder of thecompression stroke, piston rings may be provided for sealing the annularspace. However, during the power stroke, the pressure at the moment thepiston uncovers the exhaust is between 40 and pounds per square inch.While rings provided to care for the end of the compression stroke willsuffice for the early 7 portion of the power stroke, the pressure in thecylinder and in the passage is considerable up to the moment the exhaustport opens. In the operation of any engine, the angularity of theconnecting rod during the 7 major portion of the stroke causes thepressure against the end of the piston to be transierred in part to, thecylinder wall through the piston, and against that wall of the cylinderwhich is on the side opposite the position of the crankpin during thestroke. If the ratio of the pressure of the piston against the cylinderwall to that against the end of the piston is greater than the ratio ofthe area of the passage to the area of the piston, adequate sealing willbe provided. Analysis of these ratios will show that after the pistonhas traversed 15 per centum of the power stroke, the pressure of thepiston against the cylinder wall is in excess of 15 per centum of thatagainst the end of the piston. Hence, if rings are so located on thepiston that they are between the exhaust port and the passage port untilthe piston has made 15% of its power stroke, the area or" the passageport may be fully 15% that of the area of the piston. Therefore, by sodirecting the rotation of the crankshaft that the crankpin is that sideof the axis of the cylinder extended opposite the passage port duringthe power stroke, a multiplicity of piston rings will not be required.

In the accompanying drawings, I illustrate three types of exit of thepassage where it joins the closed end of the cylinder. In one the flowis from the passage along a plane at a right angle to the axis of thecylinder. In another, the mouth of the passage is directed along theaxis of the cylinder. types of passage mouth are arranged incombination.

In the drawings:

Fig. l is an elevation in section of one form of my improved engine, thesection being taken along line il of Fig. 3. In the figure, the mouth ofthe passage is along a plane approximately normal to the axis of thecylinder. The piston is shown at the end of the compression stroke.

Fig. 2 is an elevation in section of the engine of Fig. 1, the sectionbeing taken along line 22 of Fig. 4. In this figure, the piston is atthe end of its power stroke.

Fig. 3 is a plan in section of the engine of Figs. 1 and 2, the sectionbeing taken through the combustion space along line 3-3 of Fig. 1.

Fig. i is a plan in section of the engine shown in the previous figures,the section being taken along line 1-4 of Fig. 2, and as this sectionwould appear with the piston in the position of Fig. 2.

Fig. 5 is an elevation in section of an alternate form of my invention,the section being taken along line 5-Ei of Fig. 6. In this figure thepiston has started to open the passage port as it nears the end of thepower stroke.

Fig. 6 is a plan in section of the engine of Fig.

5, the section being taken along line 6-6 of Fig. 5.

Fig. '7 is a fragmentary sectional elevation of another alternate formof my improved engine,

the section being taken along line 'i-l of Fig. 8.

Fig. 8 is a plan in section of the engine of Fig. 8, the section beingtaken aong line 38 of Fig. 7.

Figs. 9, l0 and 11 are diagrammatic representations of the sequence ofthe positions of the piston as the various ports are opened toward theend of the power stroke.

Similar numerals refer to throughout the several drawings.

In the figures, the cylinder is designated by the numeral B2. Indiagrams tii it is shown at tached to crankcase 33. Within the cylinderis the piston l5, provided with th port i5 adapted to establishcommunication between the interior of the piston and the passageprovided in the wall of the cylinder, when port 55 is in registrationwith the passage port ii. Through the interior of the piston,communication is established between the crankcase i3 and passage l6,

similar parts In a third arrangement, the above two as illustrated inthe diagram Fig. 10. Passage 7;

lB extends lengthways of the cylinder; and joins the closed end of thecylinder by way of the mouth is or H3 or both in combination asshown inFig. 7.

In the wall of cylinder I2, is provided the bypass Zil partitioned frompassage it The by-pass is in direct communicationwith the crankcase I3,and is provided'with the by-pass port 21 in the wall of cylinder E 2.Integral with piston M is the deflecting plate. 22, adapted. to directthe gases entering the cylinder from port 29 toward the cylinder head.Diametrically opposite port there is provided the exhaust port 23 in thewall of cylinder I2. Spark plug 2d provides for ignition of that portionof the mixture in. the immediate vicinity of port I11, and spark plug 23' provides for ignition of themixture in clearance space [9 (Fig. 1);

Piston It is linked to the crankshaft 25 by means of the connecting-rod26, the lower end of rod 26 being journalled to crankpin 21 and theupper end of the rod journalled to piston pin 28. The piston is providedwith three sets of piston rings. Rings 29 function to seal the outer endof the piston M, as is customary in all gas engines. Rings 39 sealthatend of the piston nearest the crankcase l3. Rings 3| function. toseal the passage'between the piston and the cylinder against flow ofgases from port H. to port 23, during the later portion of thecompression. stroke and the early portion of the power stroke. Theposition of rings 3| in relation .to ports I7 and 23 should be noted inFig. 1. Attention is directed to the direction of rotation of thecrankshaft, as indicated by the curved arrows, in relation to theposition of the passage port ll, (Figs. 5, 9, l0 and 11).

In the cylinder and the various passages and ports in communicationtherewith, the fresh mixture of fuel and air is designated by arrowswith shanks of solid lines, while exhaust gases are designated byarrowshaving shanks comprisedof broken lines.

In the operation of my improved engine, a combustible mixture of fueland air is charged a into the crankcase or other pre-compression chamberby one of the several methods customarily provided therefor. The exactmethod of charging the crankcase or pre-co-mpression chamber isimmaterial to the operation of an en.- gine incorporating my improvedconstruction. The following sequence of operations comprises theremainder of the cycle.

A charge of fuel and air having been ignited in the combustion space,the ensuing explosion drives the piston toward the crankcase, andcompresses a mixture of fuel and air trapped. in the crankcase. As thepiston approaches the end of this, the power stroke, it uncovers exhaustport 22 as shown in Fig. 9, and the pressure within v the cylinderdrives the products of combustion outward through the port. Furthermovement of the piston carries it to the position of Fig. 10 with portE5 in registration with port H. The pressure within the crankcase l3drivesthe mixture therein through ports [5 and IT into passage !5 and,therethrough, into cylinder i2 through the. mouth 3. Further movementvof the piston uncovers port 2!, permitting gases from crankcase i 3 toflow into cylinder l2 through by-pass 26 and port 2|. As the enter.-'ing gases impinge against deflector 22, they are turned toward theclosed end of the cylinder. During the next stroke of the piston,toward'the closed end of the cylinder, the ports 2],. I! and 23 areclosed in the order given, and the mixture is compressed into theclearance space H! and the passage 16. Slightly in advance of thecompletion of the compression stroke, sparks are generated at the pointsof. plugs 24 and 24- igniting the mixture and starting another cycle.

As is well known in the art, the out-flow of exhaust gases through port23 has a tendency, due to inertia, to produce a partial vacuum incylinder 12. This effect, together with the new mixture entering throughports ll and 2! from the crankcase l3 insures a full charge ofcombustible mixture when the engine is operating at full throttle. Whenthe entrance of fresh mixture to the crankcase is partially closed bythrottling, the reduction of the volume of mixture within the crankcaseresults in a lowered pressure therein as compared to the crankcasepressure at full throttle, i. e-., when the entrance to the crankcase isfully open. Because of the low L crankcase pressure due to throttlingthe flow of freshv mixture through ports I! and 2| is reduced and may beso small as to be insufficient to fully overcome any vacuum in thecylinder.

Should the volume of fresh mixture entering passage l6" and cylinder I2from crankcase 53 be insuificient to' raise the pressure in the cylinderto that of the atmosphere, the direction of flow of gases through port23 will be reversed and exhaust gas-will enter the cylinder from theexhaust passages. This will result in the content of the cylinderbecoming a mixture comprised of a considerable proportion of products ofcombustion, with little fuel and air. Asthe proportion of exhaust gasesis increased; the ignition of the content of fuel becomes moredifficult. It is customary, in the operation of the two-cycle engine, toinsure ignition at lowthrottle by increasing the proportion of fuel inthe mixture. This. results in-muchunburned fuel passing out through theexhaust port with. consequent high fuel consumption and a foul smellingexhaust. Another result of dilution of the fresh charge with exhaustgases is slow burning of the ignited fuel and the extension of theperiod of inflammation until the incoming charge is ignited and themixture is fired prematurely with resulting explosions in the crankcase.This phenomenon, popularly known as back-firing, is one of theobjectionable features of the two-cycle engine with base or crankcasecompression.

It is evident to the most causal of observers that the engine hereinillustrated and described will not be subjected to the diificulties ofignition above noted. No matter how low the engine may be throttled,there is certain to be fresh mixture, undiluted by exhaust gas, in thatportion of' passage it near port 51. Hence, there will be assured anignitable mixture surrounding the ignition points of spark plug 24 underall throttle positions. Thus there is assured smooth operation at lowthrottle because of the certainty of firing every charge even when theengine is idling without other load than the friction of its ownmechanism.

In order to provide means for preventing the passage of gases from portll around the piston to exhaust port 23, I provide piston rings 3!. Withthe crankshaft turning counterclockwise, as indicated by the curvedarrow near crankshaft 25, the angul'arity of the connecting rod 26 willcause. piston 14- to be pressed against the wall of cylinder 12 on thatside provided with exhaust port 23.. As hereinbefore described, pressurein the: cylinder does not begin to rise, during the compression stroke,until after port 23 has been covered by piston It. For a short space ofthe compression stroke the pressure generated around the piston fromport ll to port 2 3.

is sufficiently low that the lubricating oil between the piston and thecylinder provides an ample seal to prevent the passage of, gases By thetime the pressure in the cylinder and passage it has risen sufiicientlyto cause leakage by the piston, rings 3i have passed port l1, andprovide an efficient seal during the balance of the compression stroke.

During the power stroke, rings 3| seal against leakage between ports I1and 23 until these rings pass port ll. By that time the piston hasadvanced sufficiently to swing the connecting rod 26 to an anglesufficient to cause piston l4 to be pressed against that portion of thecylinder wall contiguous to port I1, and with suflicient force to sealthe contacting surfaces against leakage frcm port ll around the piston.This feature assumes increasing importance as the clearance between thepiston and the cylinder increases with wear.

In the alternate form of my improved engine shown in Figs. 5 and 6, Ihave extended passage 56 across the top of the cylinder and provided itwith a mouth l8 surrounding the axis of the cylinder extended. By thisarrangement I promote stratification of the fresh mixture and theout-going exhaust gases. I also promote, by the arrangement of the mouthl8, the unidirectional flow of both the exhaust and the mixture enteringthe cylinder.

In Figs. 7 and 8 I show an arrangement of the exit from the passage l 6,with both the mouth [8 of Figs. 1-4, and the mouth l8 of Figs. 5 and 6employed in combination.

I claim:

1. In a two-cycle gas engine, the combination with a cylinder providedwith a conduit leading from a port provided in the cylinder wall midwayin the length of the cylinder to the: space between the piston and theclosed end of the cylinder when the piston is at the end of itscompression stroke the conduit open continuously to the cylinder, of apiston reciprocating in the cylinder and provided with a port in itslateral wall adapted to register with the conduit port when the pistonis at the end of its power stroke, a crankcase attached to the cylinder,the registration of the piston port with the conduit port adapted toprovide communication between the conduit and the crankcase, a by-passprovided in the lateral wall of the cylinder and leading from thecrankcase to' a second port provided in the cylinder wall midway of thelength of the cylinder, an exhaust port provided in that wall of thecylinder diametrically opposite the by-pass port, and the piston adaptedto uncover the ports in the following sequence; first, the exhaust port;second, the conduit port and third, the by-pass port. 3

2. In a two-cycle gas engine, the combination with a cylinder having ahead attached to one end thereof and a crankcase attached to the otherend and having a conduit provided in the lateral wall of the cylinderleading from a port provided through the wall of the cylinder midway ofits length tothe interior of the cylinder just within the cylinder headthe conduit open continuously to the cylinder, of a by-pass provided inthe lateral Wall of the cylinder leading from the crankcase to asecondportprovided through the cylinder wall midway of the length thereof.

3. In a two-cycle gas engine including a cylinder fitted with a cylinderhead closing one end of the cylinder and having a crankcase attached tothat end of the cylinder opposite the cylinder head, a conduit providedin the cylinder wall and leading from a port provided through thecylinder wall midway of the length of the cylinder to an openingprovided in the cylinder head into the cylinder, the said openingsurrounding the axis of the cylinder extended the conduit opencontinuously to the cylinder, and a by-pass provided in the lateral wallof the cylinder leading from the crankcase to a second port providedthrough the wall of the cylinder.

4. In a two-cycle gas engine including a cylinder fitted with a cylinderhead closing one end of the cylinder, a conduit provided in the wall ofthe cylinder leading from a port provided through the wall of thecylinder midway of the length thereof to a bifurcated opening providedin the cylinder and. the cylinder head the conduit open at all times tothe cylinder, through both branches of said opening, one branch of saidopening extending through the lateral wall of the cylinder immediatelywithin the closed end of the cylinder, and the second branch of saidopening extending through the cylinder head to an exit therefromsurrounding the axis of the cylinder K and into the cylinder.

5. In a two-cycle gas engine including a cylinder fitted with cylinderhead closing one end of the cylinder and a crankcaseattached to that endof the cylinder opposite the cylinder head, a conduit provided in thelateral wall of the cylinder, the conduit extending through the wall ofthe cylinder head, the conduit leading from a port provided through thewall of the cylinder to a bifurcated exit therefrom into the cylinder,said conduit open continuously to the cylinder through both branches ofsaid exit, one branch of the exit extending through. the lateral wall ofthe cylinder immediately within the closed end of the cylinder, thesecond branch of said exit opening from that portion of the conduit inthe cylinder head into the cylinder, said branch of the exit surroundingthe axis of the cylinder extended, and a by-pass provided in the lateralwall of the cylinder leading from the crankcase to a second portprovided in the lateral wall'of the cylinder.

6. In a two-cycle gas engine including a cylinder with a cylinder headattached to one end of the cylinder, a conduit provided in the lateralwall of the cylinder leading from a port provided through the cylinderwall midway of the length thereof to a bifurcated passage provided inthe cylinder and the cylinder head, one branch of said passage extendingthrough the lateral wall of the cylinder immediately within the closedend of the cylinder, the second branch of said passage extending throughthe wall of the cylinder head to an exit therefrom provided in thecylinder head and surrounding the axis of the cylinder extended theconduit open at all times to the cylinder through both passages, anigniter located in the conduit near the port in the cylinder wall, and asecond igniter located in that branch of the bifurcated passage in thecylinder head and near the opening therefrom into the cylinder.

'7. In a two-cycle gas engine, the combination with a cylinder providedwith a conduit in the lateral wall of the cylinder, the conduit leadingfrom a port provided through the cylinder wall midway in the length ofthe cylinder to the space between the piston and the closed end of thecylinder when the piston is at the end of its compression stroke theconduit open at all times and continuously to the cylinder, of a pistonreciprocating in the cylinder and provided with a port through thelateral wall thereof, the piston port adapted to register with theconduit port when the piston is at the end of its power stroke, acrankcase attached to the cylinder, the registration of the piston portwith the conduit port adapted to provide communication between theconduit and the crankcase, a by-pass provided in the lateral wall of thecylinder and leading from the crankcase to a second port providedthrough the cylinder wall midway of the length of the cylinder, and theby-pass partitioned from the conduit.

8. In a two-cycle gas engine, the combination with a cylinder providedwith a conduit in the lateral wall of the cylinder, the conduit leadingfrom a port provided through the cylinder wall midway in the length ofthe cylinder to the space between the cylinder head and the piston whenthe piston is at the end of its power stroke the conduit open at alltimes and continuously to the cylinder, of a piston in the cylinderadapted to reciprocate therein, a cylinder head attached to the cylinderand closing one end thereof, the piston provided with a port through thelateral wall thereof, the piston port adapted to register with theconduit port when the piston is at the end of its power stroke, acrankcase attached to that end of the cylinder opposite the cylinderhead, the registration of the piston port with the conduit port adaptedto provide communication between the conduit and the crankcase, aby-pass provided in the lateral wall of the cylinder, the by-passleading from the crankcase to a second port provided through the wall ofthe cylinder midway of the cylinder wall, the piston adapted to uncoverthis second port when the piston is at the end of its compressionstroke, and a deflector attached to the piston and projecting therefromopposite the second port, when the piston is at the end of its powerstroke.

GEORGE W. MEREDITH.

